1Saute shrimp in 1/4 cup of the olive oil with garlic and 2 of the sliced onions, one lemon. Simmer 5 minutes.DO NOT BOIL. (or shrimp will be tough).
Remove shrimp only from pan and set aside to cool.
2Combine remaining oil,remaining sliced onions,bell pepper,jalapeno pepper, lemon, and lemon juice,mustard and remaining ingredients in a large bowl, to make a marinade sauce.
Add shrimp to sauce and marinate in refrigerator at least 24 hours..Store in refrigerator in a large glass jar with a lid..